Oscillator system



April 24, 1934. J 5 ow 1,955,739

OSCILLATOR SYSTEM Filed March 15, 1933 INVENTOR .Jnmzgsflfiow. BY

a/M ATTORNEY Patented Apr. 24, 1934 OSCILLATOR SYSTEM Jennings B. Dow,

Application March 15,

4 Claims.

Long Beach, Calif.

1933, Serial No. 660,966

(Granted under the act of March 3, 1883, asv

amended April 30,

My invention relates broadly to electron tube oscillator systems.

One of the objects of my invention is to provide a simplifiedarrangement of an electroncoupled oscillator circuit when, for example,it is desired to maintain certain elements other than the cathode at alow high-frequency potential with respect to a shield box or withrespect to earth.

Another object of my invention is to provide a low power oscillator 'ofthe electron-coupled type wherein the cathode heating system may besimplified by a special arrangement of indirectly heated cathode tubes.

Other and further objects of my invention will be understood from thespecification hereinafter following by reference to the accompanyingdrawing in which:

Fig. 1 shows one form of circuit wherein an ordinary oscillator circuitis employed but with the anode element of the electron tube atsubstantially zero high-frequency potential with respect to the shieldbox and ground.

Fig. 2 shows a detailed view of the heatercathode construction of anordinary indirectly heated cathode type of electron tube.

Fig. 3 shows another form which the heatercathode construction may take.

Fig. 4 shows an electron-coupled type of oscillator circuit employingthe principles of my invention and Fig. 5 shows another form of'suchcircuit employing the principles of my invention.

As a matter of convenience the same reference numbers will be employedto designate items 5 which have similar functions in each of thefigures.

In certain forms of electron tube oscillation generators, it isdesirable to maintain one of the elements other than the cathode at alow highfrequency potential with respect to the shield box or withrespect to ground. It is well known that any one of the elements of athree element tube type of oscillation generator may be so maintained asa low high-frequency potential provid- 5 ed the other two elements areallowed to assume such high-frequency potentials as are dictated bytheir positions in the circuit. For example, Fig. 1 shows such a circuitwherein an electron tube 1 having a cathode heater 2, a 50 cathode 3, acontrol grid 4 and an anode element 5 is connected in circuit for thegeneration of oscillations. Reference character 6 designates a resonantcircuit consisting of inductance 7 and capacity 8. One end of thisresonant circuit is 55 connected through capacity 9 and grid leakresistance 10 to the control grid 4. The other end of resonant circuit 6is connected to a point 11 which may be made common to the source ofheater energy 12, the source of anode energy 13, the shield box 14 onlya section of which is shown and to earth at 15. Reference character 16designates a by-pass capacity which offers a low reactance path for highfrequency currents between anode 5 and point 11. The cathode isconnected to a point 17 along the inductance 7.

In the circuit of Fig. 1, it will be noted that the cathode is at a highfrequency potential above that of the heater 2 by an amount determinedsubstantially by the product of the high frequency current in inductance7 and the reactance of that portion of the inductance '7 between points1'? and 11. The insulation between heater 2 and cathode 3 must beconstructed to withstand this difference of potential.

Fig. 2 shows the conventional heater-cathode construction whereinreference character 18 designates the insulating tube between the heater2 and electron emitting cathode 3.

Fig. 3 shows a modified heater-cathode construction in which the heater2 and the cathode 3 are separated by space instead of a solid insulatoras in Fig. 2. In the arrangement shown in Fig. 3, the heater 2 is asingle filament stretched between two supports 19 and 20. The cathode isheld in position by bridge wires 21 which are secured to insulatingmembers 22 which in turn are secured to the heater supports 19 and 20.The form of construction shown in Fig. 3 is desirable in cases where thehigh-frequency potential difference between the heater and cathode islarge.

The circuit of Fig. 4 is that of an'electron-coupled oscillatoremploying the principles of my invention. The basic oscillator issimilar to that of Fig. 1 except that the screen-like anode element 5 isused in lieu of the ordinary anode 5 in Fig. 1. The second anode 23 inFig. 4 is connected through resonant circuit 24, consisting of capacity25 and inductance 26, to battery 27 which in combination with battery 13supplies the second anode with energy. By-pass capacity 28 bridgesbattery 27 and offers a low reactance path for the highfre-quencyimpulses of current flowing to the second anode 23.

The circuit of Fig. 5 is similar to that of Fig. 4 except that thecathode 3 instead of being connected to inductance '7, is connected toa. separate inductance 29 which is coupled to inductance '7 forproducing the desired regenerative action for oscillation. Also, in thecircuit of Fig. 5 the work circuit of the second anode 63 consistsmerely of a suitable resistance 30.

it will be understood that while I have shown battery sources of energyfor the heaters and anode supply that any other suitable sources may beused, for example, alternating current may be employed for the heaters.Also many other obvious arrangements of the circuits are possible, forexample, any of the well known basic oscillation generators may beemployed.

While I have described my invention in certain preferred embodiments, Idesire it to be understood that modiflcations may be made and nolimitations are intended other than are imposed by the scope of theappended claims.

The herein described invention may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalty thereon.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is as follows:

1. An oscillation generator having an electron tube including anindirectly heated cathode, a heater insulated from said cathode, acontrol grid and screen-like anode, sources of supply potential andconnections thereto for actuating said tube, an input circuit connectingsaid control grid and cathode, an output circuit connecting saidscreen-like anode and cathode, means for regeneratively coupling saidcircuits, at second anode within said tube and a work circuit includedin series connection between said second anode and said screen-likeanode and means including said screen-like anode for electrostaticallyshielding the electron stream of said tube between said cathode andscreen-like anode from said second anode, and a circuit of relativelylow reactance at the frequency of the generated oscillations disposedbetween said heater and said screen-like anode.

2. An oscillation generator having an electron tube including anindirectly heated cathode, a heater insulated from said cathode, acontrol grid and screen-like anode, sources of supply potential andconnections thereto for actuating said tube, an input circuit connectingsaid control grid and cathode, an output circuit connecting saidscreen-like anode and cathode, means for regeneratively coupling saidcircuits, a second anode within said tube and a work circuit included inseries connection between said second anode and said screen-like anodeand means including said screen-like anode for electrostaticallyshielding said cathode and control grid from said second anode, and acircuit having a relatively low reactance at the frequency of thegenerated oscillations disposed between said heater and screenlikeanode.

3. An oscillation generator having an electron tube including anindirectly heated cathode, a heater insulated from said cathode, acontrol grid, a screen-like anode and a second anode, sources of supplypotential and ponnections thereto for actuating said tube, an inputcircuit connecting said control grid and cathode, an output circuitconnecting said screen-like anode and cathode, means for regenerativelycoupling said circuits, a shield box at least partly surrounding saidgenerator, circuits having a low reactance at the frequency of thegenerated oscillations between said screen-like anode and said shieldbox, and between said heater and said shield box, and output means forsaid generator disposed between said second anode and said screen-likeanode.

4. An oscillation generator having an electron tube including anindirectly heated cathode, a heater insulated from said cathode, acontrol grid, a screen-like anode and a second anode, sources of supplypotential and connections thereto for actuating said tube, an inputcircuit connecting said control grid and cathode, an output circuitconnecting said screen-like anode and cathode, means for regenerativelycoupling said circuits, a shield box at least partly surrounding saidgenerator, a work circuit disposed in series connection between saidsecond anode and said screenlike anode and circuits of low reactance atthe frequency of the generated oscillations between said screen-likeanode and said shield box and between said heater and said shield box.

JENNINGS B. now.

